Electric infrared emitter



Oct. 10, 1967 H. MOHN ETAL 3,346,723

ELECTRIC INFRARED EMITTER Filed April 20', 1964 L INVENTORS I 2 HEINRICHMOHN Y GEORG HORSTMANN ATTORNEYS.

United States Patent f 3,346,723 ELECTRIC INFRARED EMITTER HeinrichMohn, Hailer, Kreis Glenhausen, and Georg Horstmann, Bruchkobel,Germany, assignors to Heraeus Quarzschmelze G.m.b.H., Hanan am Main,Germany Filed Apr. 20, 1964, Ser. No. 360,890 Claims priority,application Germany, Apr. 27, 1963, H 44,712 3 Claims. (Cl. 219-553) Thepresent invention relates to .an electric infrared emitter whichcomprises at least two parallel radiating elements.

Infrared emitters are nowadays employed very extensively for manytechnical, scientific, and therapeutic purposes. Because of theirexcellent radiating properties, especially those infrared emitters haveproved successful in which the emitter or radiating element consists ofa tube of an opaque quartz ware, quartz glass, or a glass of a highmelting point in which an electric heating conductor is provided, forexample, in the form of a heating coil. The cross-sectional shape of thetube encasing the conductor may be circular, oval, or the like.

There are infrared emitters already known which consist of two or moreparallel radiating elements which may also be mounted in front of areflector. These infrared emitters usually have the disadvantage thattheir mechanical stability and resistance to breakage is very low.

It is an object of the present invention to provide an electric infraredemitter which is highly resistant to breakage, possesses a highmechanical stability, and may be produced in a very simple andinexpensive manner.

According to the invention, this object is attained by providing anelectric infrared emitter which comprises at least two substantiallyparallel radiating elements consisting of individual tubes of opaquequartz ware, quartz glass, or glass of a high melting point, in each ofwhich an electric heating conductor is mounted, and by connecting thesetubes containing the radiating elements by at least partly fusing themtogether along their adjacent edges. The operation of fusing the tubestogether may be carried out without any technical difliculties. Anelectric infrared emitter of this construction has a very highmechanical stability and resistance to breakage. According to apreferred embodiment of the invention one end of the tubes of theradiating elements may be closed by being fused together so that theinfrared emitter has its electrical connections at only one end. If theinfrared emitter consists, for example, of two radiating elements, theheating conductor of one element may be used as a leading or inletconductor and the heating conductor of the other element as a returnconductor for the electric current. The individual tubes encasing theheating conductors of an infrared heater according to the invention mayalso consist of different materials. Thus, for example, the tube of oneradiating element may consist of quartz ware, While the tube of anotherelement which is partly fused together with the first may consist ofquartz glass.

An infrared emitter according to the invention which consists of tworadiating elements, the tubes of which are partly fused together alongtheir contact surfaces may be employed, for example, as an ignitiondevice for heating oil in an oil furnace. The encasing tubes whichpreferably have an oval cross section then contain a heating coil. Forattaining an emitter with electric connections at only one end the tubesare fused together at one end in a manner so as to form a passage fromone tube to the other. The heating conductor then passes from theoutside into and through one tube as a leading conductor and through theother tube and back to the outside as a return conductor. At their endsadjacent to the connecting passage of the two tubes both conductors arefused 3,346,723 Patented Oct. 10, 1967 together. It is, however, alsopossible to install a leading and return conductor within each tube. Inthis case, the tubes of both emitter elements are fused closed at oneend and this end of one tube is fused together with the correspondingend of the other tube. The parallel tubes may be bent at an angle at theradiating end portion and thus form an angular infrared emitter unitwhich is composed of two radiating elements. By bending this endportion, the heat is accumulated therein so that a very high temperatureis attained for the purpose of igniting the oil.

Infrared emitters according to the invention in which the radiatingelements are fused together and are thus closed at one end may also beemployed as immersion heaters. Such an immersion heater has theparticular advantage that if the heating part thereof is bent at a rightangle to the part containing the lead-in Wires it may be used especiallyfor heating the contents of a container near the bottom thereof. Thedouble-tube unit should then preferably be bent edgewise, that is, at aright angle to the common plane of both tubes, so that, when seen in thevertical projection, the bent end portion will offer the smallestpossible surface for collecting sediments or other matter. The infraredemitters according to the invention when used in a sufficient number orin the form of larger units may also be employed for room-heatingpurposes. This requires a mass production of the individual emitterswhich may be very economically carried out when designing them accordingto the invention. They also have the great advantage of having a highmechanical stability and resistance against breakage.

The features and advantages of this invention will become more clearlyapparent from the following detailed description thereof which is to beread with reference to the accompanying drawings, in which- FIGURES 1, 2and 3 show longitudinal sections of infrared emitters according to threedifferent embodiments of the invention.

The infrared emitter as shown in FIGURE 1 comprises a pair of tubes 1which are closed at one end and are fused together at different pointsalong their adjacent edge surfaces. Both tubes 1 contain heatingconductors in the form of coils 2, the lead-in wires 3 and 4 of whichare adapted to be connected in the usual manner to a source of current.The leading and return coils of the heating conductor in each tube 1 areseparated by a strip of quartz ware or quartz glass 5.

The infrared emitter according to the modification of the invention asshown in FIGURE 2 consists of two radiating tubes 1 which are fusedtogether along the entire length of their adjacent contact surfaces andone end of each tube is fused together with the corresponding end of theother tube in a manner so as to form a continuous passage 1' from onetube to the other. Each tube 1 contains a heating coil 2 or 2',respectively, and the ends of the two coils Within the end passage 1 areelectrically connected so that one heating coil 2 forms a leadingconductor, while the other coil 2' forms a return conductor. The freeends 3 and 3' of these conductors extend through the open other ends oftubes 1 to the outside and are to be connected in the usual manner to asource of current. One part of this infrared emitter may be bent at aslight angle relative to the other.

FIGURE 3 shows another modification of the infrared emitter according tothe invention which likewise consists of two radiating tubes 1 which arefused together along their entire length and are connected at one end toform a passage 1'. The difference between this infrared emitter and thatas shown in FIGURE 2 is the fact that its lower portion is bent at aright angle to the upper part and that the coil-shaped parts 2 and 2' ofthe heating conductors are only located in this bent end .-.portion from:whichQthey-lead as straight wires to the connecting ends 3 and 3'.

Although our invention has been illustrated and described with referenceto the preferred embodiments of numerous modifications within the scopeof the appended claims.

Having thus fully disclosed ourinvention, claim is:

1. An electric infrared radiation emitter comprising a plurality ofsubstantially parallel radiation permeable tubes of a material selectedfrom the group consisting of opaque quartz ware, quartz glass and highmelting point glass, said tubes being fused together at a plurality ofpoints along their adjacent surfaces, each tube having one end fusedtogether with a similar end of another tube to What,v we

define a common passage between said tubes, said tubes being bent at alocation intermediate to their fused ends and their opposite ends toposition the length portions of said tubes between their fused endsandthe bending location at a predetermined angle with respect to theremaining length portions of said tubes, an electrical resistanceheating coil disposed within each of said tubes for extensionitherein,said heating coil being approximately equal in diameter to the internaldiameter ofits associated tube, and an electrical conductor extendingthrough said passage and conductively connecting said heating elementstogether in series each heating coil having a lead conductor extendingfrom the end of its associated tube remote from the fused. end thereofand disposed for connection to an external source, of electricity forener- 4 gization of the heating coil thereby to generate and emitinfrared radiation.

2. The electric infrared emitter according to claim 1 wherein said tubesare bent at a right angle at said bending location.

3. The electric infrared emitter according to claim 2 wherein theheating coil for each tube extends within the limits of the lengthportion thereof adjacent to the fused end of the, tube and the leadconductor of said heating coil extends through the .remaininglengthpOrtiOn of the tube and-out the end thereof remote from the fused end.

References Cited UNITED STATES PATENTS 1,548,305 8/1925 -Dalton 338-268X 1,671,592 5/1928 Kercher et al. 219-523 2,059,835 11/1936 Worthing etal. 219-354 X 2,680,183 6/1954 Gomersall 338-273 2,703,833 3/1955 Vanvor338-28 2,715,675 8/1955 Macksoud 338-268 X 2,995,645 8/1961 Rankin219-353 X FOREIGN PATENTS 503,203 3/ 1939 Great Britain.

714,436 8/ 1954 Great Britain.

838,101 6/ 1960 Great Britain.

RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. V. Y. MAYEWSKY, Assistant Examiner.

1. AN ELECTRIC INFRARED RADIATION EMITTER COMPRISING A PLURALITY OFSUBSTANTIALLY PARALLEL RADIATION PERMEABLE TUBES OF A MATERIAL SELECTEDFROM THE GROUP CONSISTING OF OPAQUE QUARTZ WARE, QUARTZ GLASS AND HIGHMELTING POINT GLASS, SAID TUBES BEING FUSED TOGETHER AT A PLURALITY OFPOINTS ALONG THEIR ADJACENT SURFACES, EACH TUBE HAVING ONE END FUSEDTOGETHER WITH A SIMILAR END OF ANOTHER TUBE TO DEFINE A COMMON PASSAGEBETWEEN SAID TUBES, SAID TUBES BEING BENT AT A LOCATION INTERMEDIATE TOTHEIR FUSED ENDS AND THEIR OPPOSITE ENDS TO POSITION THE LENGTH PORTIONSOF SAID TUBES BETWEEN THEIR FUSED ENDS AND THE BENDING LOCATION AT APREDETERMINED ANGLE WITH RESPECT TO THE REMAINING LENGTH PORTIONS OFSAID TUBES, AN ELECTRICAL RESISTANCE HEATING COIL DISPOSED WITHIN EACHOF SAID TUBES FOR EXTENSION THEREIN, SAID HEATING COIL BEINGAPPROXIMATELY EQUAL IN DIAMETER TO THE INTERNAL DIAMETER OF ITSASSOCIATED TUBE, AND AN ELECTRICAL CONDUCTOR EXTENDING THROUGH SAIDPASSAGE AND CONDUCTIVELY CONNECTING SAID HEATING ELEMENTS TOGETHER INSERIES EACH HEATING COIL HAVING A LEAD CONDUCTOR EXTENDING FROM THE ENDOF ITS ASSOCIATED TUBE REMOTE FROM THE FUSED END THEREOF AND DISPOSEDFOR CONNECTION TO AN EXTERNAL SOURCE OF ELECTRICITY FOR ENERGIZATION OFTHE HEATING COIL THEREBY TO GENERATE AND EMIT INFRARED RADIATION.